Procognitive window 10 – Blue light, friend or foe?
There is no clear answer to this question, blue light can be our ally or our enemy. However, it depends on when we expose ourselves to blue light, or white light containing a blue spectral component, what the spectral pattern of such light looks like, and also what range of specific wavelengths of blue light we are talking about.
In any case, blue light has become a much discussed topic in recent years. And most often in connection with its harmfulness in the evening before going to bed and at night, and also for our eyesight. But blue light is also very important to us.
Blue light is a natural part of the spectral composition of sunlight and is absolutely crucial for us during the day. It gives the body a signal that it is daytime and what part of the day it is. This already implies that exposure to blue light in the evening and at night will give the body the wrong information that it is the day, thus disrupting circadian rhythms and suppressing the secretion of the hormone of darkness, melatonin. On the other hand, during the day, exposure to light with a proportion of blue or cyan light in the so-called melanopic region fixes and intensifies our circadian rhythm, stimulates our organism, increases vitality and improves the cognitive functions and mood.
In general, therefore, two spectral regions of blue light should be distinguished:
- Melanopic cyan region within the 460–500 nm wavelength range
- Harmful blue light area (HBL) in the 415-455nm wavelength range
Harmful blue light in the evening before going to bed and at night
Natural daylight, the sun, emits a full and uniform spectral composition during the day, from violet to red; therefore it contains blue light in both of the above spectral regions. The melanopic area is the photosensitivity area of the ganglion cells of the retina that contain the pigment melanopsin, which is most sensitive to wavelengths in the cyan spectral region with a peak at 480 nm. The presence of this energy is therefore absolutely essential during the day, but in the evening and at night it is biologically toxic. When selecting electric artificial lighting for daytime use, it is therefore very important to emphasise sufficient radiation in the cyan spectral region. In the evening and at night you should look for light sources that do not contain any blue, cyan or green energy.
What harm blue light does to our eyes
The harmful blue light (HBL) region should be of particular concern if the light source we use is not balanced in its spectral power distribution and involves a large amount of emission in this region, or in the415-455 nm range, without sufficient radiation in the red photobiomodulation region. It has been confirmed that even prolonged exposure to low-intensity blue light in the region of up to 455 nm, without compensation by red energy in the spectral power distribution, can cause damage to ocular structures (especially the retina) and thus contribute to the development of eye diseases such as macular degeneration.
Recommendation:
Blue light and circadian rhythms:
- Melatonin: a sleep hormone whose production is suppressed by blue light throughout its range
- Circadian rhythm: blue light in the evening and at night disrupts our internal 24-hour cycle and the quality of our sleep, but the presence of azure light during the day is essential and promotes sleep.
- Implications: chronic exposure to blue light in the evening can lead to insomnia, fatigue, reduced productivity and a range of illnesses
How to protect yourself from the harmful effects of blue light
- avoid light sources containing blue and green wavelengths and the use of mobile phones, tablets and computers 90 minutes before bedtime.
- Use blue light filters: activate night mode or a software filter on your devices, or get special blue light filter glasses, but only wear them in the evening and at night.
- Choose appropriate lighting in the bedroom: for 90 minutes before going to bed, only use a dim orange light without blue light and green light to prepare your body for sleep.
- Create a relaxing bedtime ritual: reading a book, taking a warm bath or meditating will help you relax and prepare for sleep.
- Expose yourself to daylight: during the day, try to maximise exposure to daylight, take a walk, walk at least part of the way to work outside in the sun, and try to sit as close to a window as possible in the office.
- Choose the right lighting for the job and for the activity: if there is a lack of daylight, use artificial light during the day with a balanced spectral power distribution and plenty of red region light, ideally bounced off the ceiling or so that the light does not dazzle you.
- Protect your eyes from blue light damage: replace intense blue light artificial light sources that do not emit plenty of red light with ones that have a balanced spectrum extending into the red or infrared parts of the spectrum. Use software filters that reduce blue light emission from displays (the displays have a yellowish tint). This also helps avoid the dry eye syndrome.
Conclusion:
Blue light is part of our lives and has a significant impact on us. If we expose ourselves to blue light in the right way, it can bring us many benefits. However, if we expose ourselves to excessive quantities of blue light or in the wrong way, it can have negative effects on our vitality, overall health and eyesight.
